Mono- and tetra-nuclear copper complexes bearing bis(imino)phenoxide derived ligands:Catalytic evaluation for benzene oxidation and ROP of ε-caprolactone

Complexes of the type [Cu(L)₂] (1) and [Cu₄L₂(μ₄-O)(OAc)₄] (2) have been obtained from the reaction of the phenoxydiimine 1,3-(2,6-R²₂C₆H₃N=CH)₂-5-R¹ C₆H₂OH-2 (LH) (where R¹ = Me, tBu, Cl; R² = Me, iPr) with copper(II) acetate [Cu(OAc)₂]; changing the molar ratio of the reactants affords differing amounts of 1 or 2. Reaction of the parent dialdehyde [1,3-(CHO)₂-5-MeC₆H₂OH-2] with [Cu(OAc)₂] in the presence of Et₃N afforded, following work-up, a polymeric chain (3) comprising {[Cu₂(OAc)₄]OAc}n, HNEt₃ and MeCN. The crystal structures of 1 (R¹ = Me, R² = iPr 1a; R¹ = Cl, R² = iPr 1b), 2 (R¹ = Me, R² = Me 2a; R¹ = Me, R² = iPr 2b; R¹ = tBu, R² = Me 2c; R¹ = Cl, R² = Me 2d; R¹ = Cl, R² = iPr 2e; R¹ = tBu, R² = iPr 2f) and 3 are reported (synchrotron radiation was necessary for 3). The magnetic properties of the cluster 2b are presented. Complexes of type 2 and 3 were screened for the ring opening polymerization (ROP) of ε-caprolactone, with or without benzyl alcohol present, under a variety of conditions, however only trace polymer was isolated. The electrochemistry of all complexes was also investigated, together with their ability to catalyze benzene oxidation (using hydrogen peroxide); although low conversions were observed, the tetra-nuclear complexes exhibited excellent selectivity

Functionalized Mesoporous Silica as Doxorubicin Carriers and Cytotoxicity Boosters

Mesoporous silica nanoparticles (MSNs) bearing methyl, thiol or glucose groups were synthesized, and their encapsulation and release behaviors for the anticancer drug Doxorubicin (Dox) were investigated in comparison with nonporous homologous materials. The chemical modification of thiol-functional silica with a double bond glucoside was completed for the first time, by green thiol-ene photoaddition. The MSNs were characterized in terms of structure (FT-IR, Raman), morphology (TEM), porosity (nitrogen sorption–desorption) and Zeta potential measurements. The physical interactions responsible for the Dox encapsulation were investigated by analytic methods and MD simulations, and were correlated with the high loading efficiency of MSNs with thiol and glucose groups. High release at pH 5 was observed in most cases, with thiol-MSN exhibiting 98.25% cumulative release in sustained profile. At pH 7.4, the glucose-MSN showed 75.4% cumulative release, while the methyl-MSN exhibited a sustained release trend. The in vitro cytotoxicity was evaluated on NDHF, MeWo and HeLa cell lines by CellTiter-Glo assay, revealing strong cytotoxic effects in all of the loaded silica at low equivalent Dox concentration and selectivity for cancer cells. Atypical applications of each MSN as intravaginal, topical or oral Dox administration route could be proposed

Metal–organic frameworks based on tri- and penta-nuclear manganese( ii ) secondary building units self-assembled by a V-shaped silicon-containing dicarboxylate

International audienc

Di- and tetracarboxylic aromatic acids with silane spacers and their copper complexes: Synthesis, structural characterization and properties evaluation

International audienc

From Amorphous Silicones to Si-Containing Highly Ordered Polymers: Some Romanian Contributions in the Field

Polydimethylsiloxane (PDMS), in spite of its well-defined helical structure, is an amorphous fluid even at extremely high molecular weights. The cause of this behavior is the high flexibility of the siloxane backbone and the lack of intermolecular interactions attributed to the presence of methyl groups. These make PDMS incompatible with almost any organic or inorganic component leading to phase separation in siloxane-siloxane copolymers containing blocks with polar organic groups and in siloxane-organic copolymers, where dimethylsiloxane segments co-exist with organic ones. Self-assembly at the micro- or nanometric scale is common in certain mixed structures, including micelles, vesicles, et cetera, manifesting reversibly in response to an external stimulus. Polymers with a very high degree of ordering in the form of high-quality crystals were obtained when siloxane/silane segments co-exist with coordinated metal blocks in the polymer chain. While in the case of coordination of secondary building units (SBUs) with siloxane ligands 1D chains are formed; when coordination is achieved in the presence of a mixture of ligands, siloxane and organic, 2D structures are formed in most cases. The Romanian research group’s results regarding these aspects are reviewed: from the synthesis of classic, amorphous silicone products, to their adaptation for use in emerging fields and to new self-assembled or highly ordered structures with properties that create perspectives for the use of silicones in hitherto unexpected areas